remove duplicate dictionary lookups

src/IdentityServer/Configuration/DependencyInjection/Options/DynamicProviderOptions.cs

@@ -76,7 +76,7 @@ public void AddProviderType<THandler, TOptions, TIdentityProvider>(string type)
     /// <returns></returns>
     public DynamicProviderType? FindProviderType(string type)
     {
-        return _providers.ContainsKey(type) ? _providers[type] : null;
+        return _providers.GetValueOrDefault(type);
     }
 
     /// <summary>

src/IdentityServer/Endpoints/Results/ProtectedResourceErrorResult.cs

@@ -48,9 +48,9 @@ public Task WriteHttpResponse(ProtectedResourceErrorResult result, HttpContext c
         var error = result.Error;
         var errorDescription = result.ErrorDescription;
 
-        if (Constants.ProtectedResourceErrorStatusCodes.ContainsKey(error))
+        if (Constants.ProtectedResourceErrorStatusCodes.TryGetValue(error, out var code))
         {
-            context.Response.StatusCode = Constants.ProtectedResourceErrorStatusCodes[error];
+            context.Response.StatusCode = code;
         }
 
         if (error == OidcConstants.ProtectedResourceErrors.ExpiredToken)

src/IdentityServer/Hosting/LocalApiAuthentication/LocalApiAuthenticationHandler.cs

@@ -246,10 +246,9 @@ protected override Task HandleChallengeAsync(AuthenticationProperties properties
                 var nonce = Context.Items["DPoP-Nonce"] as string;
                 Context.Response.Headers[HttpHeaders.DPoPNonce] = nonce;
             }
-            else if (properties.Items.ContainsKey("DPoP-Nonce"))
+            else if (properties.Items.TryGetValue("DPoP-Nonce", out var nonce))
             {
                 // this allows the API itself to set the nonce
-                var nonce = properties.Items["DPoP-Nonce"];
                 Context.Response.Headers[HttpHeaders.DPoPNonce] = nonce;
             }
         }

src/IdentityServer/Test/TestUserStore.cs

@@ -103,9 +103,9 @@ public TestUser AutoProvisionUser(string provider, string userId, List<Claim> cl
                 filtered.Add(new Claim(JwtClaimTypes.Name, claim.Value));
             }
             // if the JWT handler has an outbound mapping to an OIDC claim use that
-            else if (JwtSecurityTokenHandler.DefaultOutboundClaimTypeMap.ContainsKey(claim.Type))
+            else if (JwtSecurityTokenHandler.DefaultOutboundClaimTypeMap.TryGetValue(claim.Type, out var value))
             {
-                filtered.Add(new Claim(JwtSecurityTokenHandler.DefaultOutboundClaimTypeMap[claim.Type], claim.Value));
+                filtered.Add(new Claim(value, claim.Value));
             }
             // copy the claim as-is
             else

test/IdentityServer.IntegrationTests/TestFramework/TestBrowserClient.cs

@@ -268,8 +268,7 @@ public string this[string key]
     {
         get
         {
-            if (Inputs.ContainsKey(key)) return Inputs[key];
-            return null;
+            return Inputs.GetValueOrDefault(key);
         }
         set
         {